U.S. Special Representative for Syrian Engagement James Jeffrey recounted to reporters on Wednesday "five examples of state-on-state violence" over the past six weeks in Syria. These included recent tensions between the various armed forces present in the country, as well as recent attacks such as the accidental shootdown of a Russian military plane by allied Syrian defenses reacting to an Israeli air raid and an Iranian missile strike targeting militants just three miles from U.S. troops.

"Many of you have covered the Middle East for many years, and you know that you get all of the time sub-state actors and failed states and ungoverned territories and counterterrorism and civil wars and insurgencies and that sort of thing, but you don’t normally see this kind of state-on-state potential for conflict," Jeffrey said.

"And so I think everybody is concerned," he added.

While world powers intervened at the very onset of unrest in Syria—where the U.S. and its regional allies sponsored armed opposition to a government they accused of human rights abuses—the latest phase of the seven-year war has threatened to pit several of these participating nations directly against one another. At least three of the instances recounted by Jeffrey included the potential for direct U.S. military action.